We have reached max X-MAX with the Parts Express passives. So weighted and tuned correct they do not pass mustard. We are very close to picking up pieces of cone material off of the ground. Crazy Excursion during DTS formatted movies. Music is good, and bass response is tight, and punchy in the upper volume levels. So far these subs are very impressive, subtle low frequency passages during movie play back are very defined and amazing, I would recommend the use of these drivers for any application.
So as far as new passives go I'm looking at these brands.
http://www.tcsounds.com/tcvmp.htm#specs
Seems they are one of the few manufacturing high X-MAX passives, 80mm peak to peak, and 500 to 2500 gram weight capacity.
Specifications
3" wide variable mass load adaptor
500 grams up to ~2500 grams of variable mass (90 gram iterations)
xmax of 40mm (one way linear compliance)
Single ultra wide 10" poly-cotton spider
Cast aluminum basket with high gloss metallic powder coating
Tall (NBR) surround for high excursion and better longevity than foam
Includes up to 2000 grams of selectable mass washers
High quality thermal flexible epoxies to ensure longevity
Rigid lightweight brushed aluminum cone
Hand built in our San Diego, CA factory
*mounting depth includes 2.0" extra spacing for excursion
Thiele Small Parameters
12" TC-VMP
Vap0.0 Dia250mm Vas0.0l V-Fs4Hz-24Hz cms0.0m/N V-mms500g-2500g
15" TC-VMP
Vap0.0 Dia325mm Vas0.0l V-Fs4Hz-24Hz cms0.0m/N V-mms500g-2500g
18" TC-VMP
Vap0.0 Dia390mm Vas0.0l V-Fs4Hz-24Hz cms0.0m/N V-mms500g-2500g
This is the other brand I'm looking at, and I have seen threads on th LH forum in regards to their use. Stryke Audio SA-PR18-1600. But I think production has stopped for I can't find a seller of them new. The link below is no longer carrying them.
http://www.acoustic-visions.com/~acoustic/products/passive_radiators/stryke_pr18/indexold.shtml
So needless to say the volume control has been regulated depending on the source input.
The LH member who is helping me tune these bad boys has run the Stryke Audio 18" in a simulation and it seems to do the trick. Stated below are the results. This is the passive I would like to use if I can find some????
The above PR will work just fine, but the cost is much higher, and they are out of stock on them.
I modeled the 1600g in 5 cu ft, it looks absolutely bullet proof - Group delay is very low, power handling is off the chart, cone excursion for both is safe at 105db+ from 20Hz on up....dayum....
Worthy of discussion in public. I'm only parroting what I see in ISD - I'd like to hear others' views...
SA-PR18-1600
FS 4hz
Mms 1600 grams
Qms85
SD 1200cm^2
Vd 9L
Vas 1840L
Xmax 76mm p-p
If anyone can help with this issue in finding, or wanting to sell a couple of the Stryke Audio passives let me know.
J/S-S1A